Author Topic: ignition or fuel problem help needed  (Read 1259 times)

Offline chaz

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ignition or fuel problem help needed
« on: 20.05. 2009 21:54 »
have a Boyer electronic ignition box fitted , a pair of new coils , plugs and leads. Also have now a new pair of Amal carbs.

the bike was running fine untill I decided to take it for a ride, then decided to go down on one cylinder.

If I lift the plug cap up and just rest it ontop of the right hand plug both cylinders fire fine, take off or push on to plug and it stops the cylinder firing. left hand side is fine.

anyone an idea what the problem is?
I suspected carbs as I have changed all electrics, it seems that the motor runs fine with a loose plug cap, would this be too much fuel and the loose plug cap generates a bigger spark???

confused *ex*
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Offline beezalex

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Re: ignition or fuel problem help needed
« Reply #1 on: 20.05. 2009 22:00 »
Have you looked at the plugs? This is typically symptomatic of a fouled plug, so yes, it is a carb problem.  Somewhere in the throttle range, you're too rich.  This is not uncommon with new carbs.  They are rarely jetted correctly out of the box.
Alex

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Richard

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Re: ignition or fuel problem help needed
« Reply #2 on: 20.05. 2009 22:08 »
evening all
with the boyer I believe that both plugs fire at the same time so to check the leads and caps swap the leads over and see if the problem transfers to the other side at least it will rule that out
Richard

Offline chaz

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Re: ignition or fuel problem help needed
« Reply #3 on: 20.05. 2009 22:55 »
tried swapping the plug leads over before fitting new carbs , at the time it didnt make any difference hence new carbs. will try this again.
the carbs have taken 4 months to appear from Amal Salisbury, someone else I know ordered his and the float camber screws fell out on the first ride!! losing the float, brass sleeve and viton tipped needle.

the carbs have been  built to the standard bike spec applicable for that year. so jetting should be ok, bike only shows 9000 miles and by condition I would say thats about right, although when reimported it was fitted with Boyer but I think the original carbs were 'borrowed', and the dealer fitting the boyer didnt even change the air filters but made a remark that they were dirty!!
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Offline BSA_54A10

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Re: ignition or fuel problem help needed
« Reply #4 on: 21.05. 2009 01:00 »
No it signifies a fouled plug.
The old ruse for cleaning a fouled plug was to hold the cap about 1/4" away from the end of the plug.
This will cause the plug to fire and you continue to old it there for 5 minutes or so till the plug runs cleanly.
AS you have only 1 carb it is fairly well a physical impossibility to be running so rich on one side to foul the plug while running clean on the other .
Could be a bad plug or a bad lead or crud in the slip ring on the maggy
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Trevor

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Re: ignition or fuel problem help needed
« Reply #5 on: 21.05. 2009 10:56 »

AS you have only 1 carb it is fairly well a physical impossibility to be running so rich on one side to foul the plug while running clean on the other .

Well, if it's running rich, one plug of the pair has to foul first.

On a bike with Boyer, almost any running problem is likely to be caused by power supply to the Boyer:  low battery voltage,  loose connections or dirty switch terminals.

Also, don't be surprised if a carb bought new with recommended jettings and settings is wrong for your individual bike.  You have to follow the well-documented Amal tuning procedure.


http://www.hitchcocksmotorcycles.com/amal/mk2_conc_ht.html

Offline BSA_54A10

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Re: ignition or fuel problem help needed
« Reply #6 on: 21.05. 2009 13:54 »
New leads ?
Solid copper or spiral wound ones only. Car leads will not work for long.
New caps ? Boyer will not work very well with resistor caps.
New plugs ? I have had up to 5 go bad, straight out of the box in one day. I am still running on No 6 and that was about 25,000 miles ago.
Swap every thing left right ( one part at a time) if the problem moves then the last thing you moved is causing it.
If the problem dosn't move then it is in the carbs.                         
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Trevor